Preheat the oven to 350°F (180°C). Line a cookie sheet with parchment paper. Lightly oil the paper with coconut oil. Set aside.
Peel, mash the bananas with a fork or potato masher into a liquid puree. If too many lumps, the cookies end up dry, so mash it very well.
Measure 2/3 cup not less or more to avoid dry cookie and stir in a bowl with peanut butter and maple syrup (if added).
Stir in the quick-cooking oats (not rolled oats!) and chocolate chips. The cookie batter should be sticky, thick. If too wet, add more quick oats. If too dry, add more mashed banana.
Scoop one tablespoon of batter, slightly grease your hands with coconut oil and roll into a ball.
Place the cookie dough ball onto the prepared cookie sheet. Flatten with your hands and repeat until you have formed 10 cookies. Leave half a thumb of space between each cookie - they won't expand in the oven.
Bake for 15-18 minutes or until golden brown on sides and top. The longer you bake the cookies, the crispier they are on the edges, but the center should stay soft and moist.
Cool on the cookie rack for 10 minutes, then transfer them to a wire rack.